.d1 {
  width: 100px;
  height: 100px;
  border: 3px solid red;
  margin-left: 20px;
  font-size: 30px;
  background: url("../../day02/images/2.png");
}
.d2 {
  width: 100px;
  height: 100px;
  border: 3px solid red;
}
#a1 {
  color: red;
}
.a1 {
  color: blue;
}
p {
  background: url("../../day02/images/1.png");
}
h2 {
  color: red;
}
span {
  background-color: #ccc;
}
h3 {
  color: blue;
  font-size: 50px;
}
/*
    变量的特性
*/
h1 {
  color: red;
  background-color: pink;
  text-decoration: overline;
}
span {
  color: red;
}
/*
    选择器的嵌套
*/
ul {
  background: #ff7300;
  overflow: hidden;
}
ul li {
  list-style: none;
  float: left;
  width: 100px;
  height: 38px;
  line-height: 38px;
  text-align: center;
}
ul li a {
  text-decoration: none;
  color: #fff;
}
